It has long been my opinion that human artistic behavior is primarily
a product of sexual selection, not natural selection. People who
can sing, paint, draw, dance, etc. in a very pleasing way give
evidence of having sufficient wealth (in the form of leisure time)
to be attractive mates.

This doesn't immediately help explain any puzzling details, but if
you want to look at art from the perspective of evolutionary
psychology, I think a clear understanding of Darwin's distinction
between natural selection and sexual selection is essential.

(Usual, even stereotypical, examples of sexual selection among
other species include the antlers of the Irish elk and the tail
of the peacock. Those are physical rather than behavioral
structures, and this is another thing we need to keep in mind in
order to avoid oversimplistic application of the idea of sexual
selection.)